hg: jdk8u/jdk8u-dev/hotspot: 6651256: jstack: DeleteGlobalRef method call doesn't lead to descreasing of global refs count shown by jstack

[david.buck at oracle.com]

Changeset: 16939858a716
Author:    dbuck
Date:      2017-08-21 11:34 -0400
URL:       http://hg.openjdk.java.net/jdk8u/jdk8u-dev/hotspot/rev/16939858a716

6651256: jstack: DeleteGlobalRef method call doesn't lead to descreasing of global refs count shown by jstack
Summary: jni_DeleteGlobalRef does not really release the jni handle, instead, set the handle point to JNIHandles::_deleted_handle which holds an oop instance (java/lang/Object) in Java heap and never be GC'ed. When counting number of global reference, it counts all the handles on the chain list, which includes the already deleted ones.
Reviewed-by: zgu, sla, coleenp
Contributed-by: yumin.qi at oracle.com

! src/share/vm/runtime/jniHandles.cpp